Methods and apparatus for reducing interference

ABSTRACT

A method and apparatus for reducing interference is provided. The method may include receiving an interference indicator from a station (STA), and determining a service period end time from the interference indicator. The method may further include terminating the service period at or before the service period end time, or determining an end to the service period at the service period end time, wherein the interference indicator comprises a time indication for the service period end time or a schedule of one or more start times of interference at the STA.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application for patent claims priority to Provisional Application No. 61/385,416 entitled “METHODS AND APPARATUS FOR REDUCING INTERFERENCE AND/OR AVOIDING COLLISIONS” filed Sep. 22, 2010, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.

BACKGROUND

1. Field

The present disclosure relates generally to communication systems, and more particularly, to reducing interference.

2. Background

In order to address the issue of increasing bandwidth requirements that are demanded for wireless communications systems, different schemes are being developed to allow multiple user terminals to communicate by sharing the channel resources while achieving high data throughputs. Different wireless technologies have been adopted in several emerging wireless communications standards such as the Institute of Electrical Engineers (IEEE) 802.11 standard. IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications (e.g., tens of meters to a few hundred meters), for example, 802.11 ad/ac/a/b/g/n/v/z.

Generally, wireless communications systems specified by the IEEE 802.11 standard have a central entity, such as an access point (AP)/packet coordination function (PCF) that manages communications between different devices, also called stations (STAs). Having a central entity may simplify design of communication protocols. Further, although any device capable of transmitting a beacon signal may serve as an AP, for an AP to be effective it may have to have a good link quality to all STAs in a network.

Mobile wireless communications devices (WCD) (e.g., laptops, smartphones, STAs, etc.) may have comparatively reduced capabilities to that of a traditional AP due to factors such as cost, power, form factor, etc. For example, antenna steering capability may be limited to a small sector bound, available power may be limited, location may be variable, etc. Even with these limitations, WCDs may be asked to perform as APs to form peer-to-peer networks for various purposes, such as side-loading, file sharing, etc.

In some aspects, it is desired to reduce interference in communications between a WLAN STA and an AP. For example, WLAN STAs currently may not be able to receive packets from an access point (AP) during part of a service period (SP) due to periodic interference occurring at the STA. For example, such periodic interference may be caused by concurrent operation at the STA of a Bluetooth module and another transceiver using a different radio access technology. Therefore, improved interference signaling may be beneficial.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In accordance with one or more aspects and corresponding disclosure thereof, various aspects are described in connection with reducing interference in a communications system. The method can comprise receiving an interference indicator from a station (STA), and determining a service period end time from the interference indicator.

Yet another aspect relates to an apparatus. The apparatus can include means for receiving an interference indicator from a STA, and means for determining a service period end time from the interference indicator.

Still another aspect relates to a computer program product comprising a computer-readable medium. The computer-readable medium can include code for receiving an interference indicator from a STA, and determining a service period end time from the interference indicator.

Another aspect relates to an apparatus for communications. The apparatus can include a processing system. The apparatus may also include a service period determination module configured to receive an interference indicator from a station (STA), and determine a service period end time from the interference indicator.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other sample aspects of the invention will be described in the detailed description that follow, and in the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a communication network including aspects relating to interference signaling;

FIG. 2 is a flowchart of an aspect of a method of interference signaling;

FIG. 3 is a timeline including periodic interference and signaling occurring over time in a communication network, relating to interference avoidance;

FIG. 4 is a schematic diagram of an aspect of an architecture of a wireless communications device of FIG. 1;

FIG. 5 is a schematic diagram of an aspect of an architecture of an access point of FIG. 1; and

FIG. 6 Illustrates a block diagram of an exemplary communication system that can reduce interference, according to yet another aspect.

In accordance with common practice, some of the drawings may be simplified for clarity. Thus, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. Finally, like reference numerals may be used to denote like features throughout the specification and figures.

DETAILED DESCRIPTION

Various aspects of methods and apparatus are described more fully hereinafter with reference to the accompanying drawings. These methods and apparatus may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of these methods and apparatus to those skilled in the art. Based on the descriptions herein teachings herein one skilled in the art should appreciate that that the scope of the disclosure is intended to cover any aspect of the methods and apparatus disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be embodied by one or more elements of a claim.

Several aspects of a wireless network will now be presented with reference to FIG. 1. The wireless communication system 100 is shown with several wireless nodes or stations (e.g., STAs), generally designated as nodes 110 and 130, an access point (AP) 120, generally a WLAN device, a base station, etc., wherein the several nodes 110, 130 may communicate using several protocols 118, 124 associated with several networks 116, 122. As used herein, a wireless node 110, 130 may be referred to as a WCD, user equipment (UE), a STA, a laptop, etc. Each wireless node is capable of receiving and/or transmitting. In the detailed description that follows, the term “access point” is used to designate a transmitting node and the term “access terminal” is used to designate a receiving node for downlink communications, whereas the term “access point” is used to designate a receiving node and the term “access terminal” is used to designate a transmitting node for uplink communications. However, those skilled in the art will readily understand that other terminology or nomenclature may be used for an access point and/or access terminal. By way of example, an access point may be referred to as a base station, a base transceiver station, a station, a terminal, a node, an access terminal, acting as an access point, a WLAN device, or some other suitable terminology. An access terminal may be referred to as a user terminal, a mobile station, a subscriber station, a station, a wireless device, a terminal, a node, or some other suitable terminology. The various concepts described throughout this disclosure are intended to apply to all suitable wireless nodes regardless of their specific nomenclature.

The wireless communication system 100 may support access terminals distributed throughout a geographic region. AP 120 may be used to provide coordination and control of the access terminals, as well as access to other networks (e.g., Internet). Each STA, which may be fixed or mobile, may use backhaul services of an access point or engage in peer-to-peer communications with other STAs. Examples of STAs include a telephone (e.g., cellular telephone), a laptop computer, a desktop computer, a Personal Digital Assistant (PDA), a digital audio player (e.g., MP3 player), a camera, a game console, or any other suitable wireless node.

In one aspect, each STA 110 and 130 and access point 120 may be configured for enhanced communication by avoiding periodic interference at STA 110 and/or 130. In one aspect, interference may originate from sources, such as, but not limited to, other STAs, other transceivers associated with the STA (e.g., Bluetooth transceiver), etc; It is noted that the following interference avoidance aspects are illustrated in FIG. 1 with reference to STA 130, however, such aspects may apply as well to STA 110 or any other STA in the system. Also, this aspect is described in more detail below with reference to FIG. 3. Each STA, such as STA 110, may include an interference signaling module 132 that communicates with a service period determination module 134 on access point 120 to assist in enabling communications sessions 124 with one or more STAs 110 and 130. In particular, interference signaling module 132 may transmit a trigger frame to access point 120, and service period determination module 134 determines a time remaining until interference based on the arrival timing of the trigger frame. In some aspects, the trigger frame also indicates a start time of the service period. In one aspect, for example, STA 130 may provide service period (SP) determination module 134 with an interference schedule 138, which may define start times of each of a plurality of periodic interferences at STA 130. Thereafter, when the access point 120 may receive a trigger frame, such as an unscheduled asynchronous power save delivery (U-APSD) trigger frame, from the STA 130, service period determination module 134 may determine an amount of time remaining until interference for the service period. For example, service period determination module 134 may determine a time remaining until interference based on a timing corresponding to the transmission of a trigger frame and an amount of time left before the start of a next one of the periodic interference based on interference schedule 138. Accordingly, service period determination module 134 may attempt to terminate the corresponding service period (SP) during the time remaining until interference. In one aspect, if SP determination module 134 does not explicitly terminate the SP before the start of the next of a periodic interference, such as by a successful transmission of an SP end frame (e.g., a frame with the End of Service Period (EOSP) bit set) both STA 130 and AP 120 may implicitly assume that the SP terminates at the start of the next periodic interference.

In one aspect, the interference schedule 138 may define interference start times, which may be based on an Offset and an Interval. In such an aspect, the Offset may indicate an offset relative to a Timing Synchronization Function (TSF), such as at an initial time value “0” at which a first interference period takes place. Further, the Interval may indicate the interval at which the next occurrence of the interference starts. Additionally, the Offset and Interval parameters may allow service period determination module 134 to determine the start of an interference period at any time value of the TSF (e.g., these parameters may not be provided at TSF at time “0”).

In another aspect, interference signaling module 132 may provide SP determination module 134 with a time indication relating to when a SP may end, referred to as a SP end time indicator 146. In one such aspect, the SP end time indicator 146 may indicate a time prior to a start time of a next periodic interference at the STA. Further, for example, SP end time indicator 146 may be provided in a trigger frame. In this aspect, when service period determination module 134 receives the trigger frame, such as an U-APSD trigger frame, from the STA, service period determination module 134 may determine time remaining until next interference starts, based on SP end time indicator 146, and may attempt to terminate the SP before an end of time remaining until a next interference. Further, for example, the SP end time indicator 146 (e.g., indicating the start time of a next occurrence of interference) may be signaled as a duration D relative to a time T at which the trigger frame is transmitted, or it may be signaled in terms of a Timing Synchronization Function (TSF) value E, where E is a time value that corresponds to an end time of the service period. Further, for example, the trigger frame may include or be a U-APSD Coexistence frame that contains the end time E (or the duration D) of the service period. Additionally, although the interference depicted in FIG. 3 has a fixed periodicity and duration, this may not be the case when an SP end time indicator 146 is included in a trigger frame.

In the detailed description that follows, various aspects of the disclosure will be described with reference to any suitable wireless technology, such as Orthogonal Frequency Division Multiplexing (OFDM), Multiple Input Multiple Output (MIMO), etc. OFDM is a spread-spectrum technique that distributes data over a number of subcarriers spaced to provide “orthogonality.” Such spacing enables a receiver to recover the data from the subcarriers. An OFDM system may implement IEEE 802.11, or some other air interface standard. Other suitable wireless technologies include, by way of example, Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), or any other suitable wireless technology, or any combination of suitable wireless technologies. A CDMA system may implement with IS-2000, IS-95, IS-856, Wideband-CDMA (WCDMA), or some other suitable air interface standard. A TDMA system may implement Global System for Mobile Communications (GSM) or some other suitable air interface standard. As those skilled in the art will readily appreciate, the various aspects of this invention are not limited to any particular wireless technology and/or air interface standard.

The wireless node (e.g., 110, 130), whether an access point or access terminal, may be implemented with a protocol that utilizes a layered structure that includes a physical (PHY) layer that implements all the physical and electrical specifications to interface the wireless node to the shared wireless channel, a Medium Access Control (MAC) layer that coordinates access to the shared wireless channel, and an application layer that performs various data processing functions including, by way of example, speech and multimedia codecs and graphics processing. Additional protocol layers (e.g., network layer, transport layer) may be available for particular application. In some configurations, the wireless node may act as a relay point between an access point and access terminal, or two access terminals, and therefore, may not use an application layer. Those skilled in the art will be readily able to implement the appropriate protocol for any wireless node depending on the particular application and the overall design constraints imposed on the overall system.

Referring to FIG. 2, a flowchart defines aspects of various methodologies operable in accordance with the subject matter described herein. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the claimed subject matter is not limited by the order of acts, as some acts may occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with the claimed subject matter. Additionally, it should be further appreciated that the methodologies disclosed hereinafter and throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to computers. The term article of manufacture, as used herein, is intended to encompass a computer program accessible from any computer-readable device or media.

Referring to FIG. 2, a process 200 is depicted in which communications between an AP and a STA may be enabled to reduce, minimize and or avoid interference (e.g., periodic interference) observed at the STA. At block 202, the process may include receiving an interference indicator. For example, in an aspect, an AP may receive the interference indicator from a STA based on interference observed at the STA. In one such aspect, the interference may be periodic interference. In an aspect, the interference indicator may include an SP end time indicator, wherein the SP end time indicator may be relative to a trigger frame transmission time. In such an aspect, the trigger frame may include or be a U-APSD Coexistence frame. In another aspect, the interference indicator may include an SP duration, which may be defined by a timing synchronization function (TSF). In one aspect, the TSF may include a timer or timing value known by a plurality of stations and broadcast by the AP. In one such aspect, the AP may broadcast the TSF periodically. In another aspect, the TSF may be defined through units of microseconds. In still other aspects, the interference indicator may include an interference schedule from the STA. For example, the interference schedule may include timing information corresponding to one or more interference time periods at the STA. In some cases, the interference schedule may include or may be defined by an offset relative to a TSF and an interval before an occurrence of interference.

At block 204, the process may include determining a service period end time from the interference indicator. For example, in an aspect, the AP may determine a time remaining until the end of the SP based on the SP end time indicator or the SP duration. Further, for example, in another aspect, the AP may determine a time remaining until the end of the SP based on the interference schedule.

At block 206, in an optional aspect, the process may include terminating the service period at or before the service period end time.

At block 208, in another optional aspect, the process may include implicitly determining an end to the service period at the service period end time.

Referring to FIG. 3, a timeline 300 (not necessarily to scale) includes interference 304 observed by a STA, as well as certain signaling extending on the y-axis, and time 302 progressing on the x-axis, relating to the above-described interference avoidance processing. In an aspect, the interference may be periodic interference. In one aspect, an AP may be provided with an interference start time schedule. In one aspect, the interference start time schedule may include an Offset and an Interval. In such an aspect, the Offset may indicate an offset relative to Timing Synchronization Function 314, such as at an initial time “0”, referred to as TSF 0, at which a first interference period 304 takes place. Further, the Interval may indicate the time period from the beginning of an interference period to the next occurrence of the periodic interference 304. Additionally, the Offset and Interval parameters may allow and access point to determine the start of an interference period 304 at any value of the TSF 314.

In an example, if an access point (AP) receives a trigger frame 306 at a time T_(trigger), or 308, then a Duration, D, or a time period 312, to a start time 310 of a next occurrence of interference 304 may be calculated as follows:

D−Interval−(T _(trigger)−Offset)mod Interval

As depicted above, D, Interval, T_(trigger), and Offset may be measured using units, such as microseconds (ms), etc. Further, the AP may attempt to terminate the service period 313 at or before E=T_(trigger)+D. In one aspect, the service period 313 may include a contiguous time during which one or more downlink individually addressed frames may be transmitted to a STA and/or one or more transmission opportunities (TXOPs) are granted to the same STA. SPs can be scheduled or unscheduled. In one such aspect, an unscheduled service period may include a time period that may be started when a STA may be transmitting a trigger frame to the AP. In other words, the time E, or 310, at which the SP 313 should be terminated, or when the SP 313 terminates implicitly, may be calculated as follows:

E=T _(trigger)+Interval−(T _(trigger)−Offset)mod Interval

In other words, in one aspect, the end time E, or 310, of SP 313 (e.g., the start time of a next occurrence of interference 304) may be signaled as a duration D, 312, relative to the time T_(trigger), 308, at which the trigger frame 306 is transmitted, while in another aspect, the end time E, or 310, of SP 313 may be signaled in terms of a TSF value representing or corresponding to time E, 310. Further, the trigger frame 306 may include or be a U-APSD Coexistence frame that contains the end time E (or the duration D) of the service period, such as SP 313, which can be referred to as the Max SP TSF.

An example U-APSD Coexistence Action frame is shown as follows:

Category Action Max SP TSF Octets: 1 1 4

The U-APSD Coexistence frame may be aggregated with data frames, using an Aggregated Media Access Control Protocol Data Unit (A-MPDU). As noted above, the Max SP TSF field may be defined in units of time (e.g., microseconds).

The AP may carry out this calculation upon receipt of a trigger frame 306. In one aspect, the AP may not maintain a timer that sends a signal at every start of an interference period (e.g. the start time to the end time of each interference 304), as such a timer may be cumbersome to implement at the AP. Therefore, the AP may not compute available SPs for every STA.

While still referencing FIG. 1, but turning also now to FIG. 4, an example architecture of wireless communications device 110 or 130 (FIG. 1) is illustrated. As depicted in FIG. 4, wireless communications device 400 includes receiver 402 that receives a signal from, for instance, a receive antenna (not shown), performs typical actions on (e.g., filters, amplifies, downconverts, etc.) the received signal, and digitizes the conditioned signal to obtain samples. Receiver 402 may include a demodulator 404 that may demodulate received symbols and provide them to processor 406 for channel estimation. Further, receiver 402 may receive signals from multiple networks using multiple communication protocols. In one aspect, receiver 402 may receive a signal from a network using at least one of: CDMA, WCDMA, TDMA, TD-SCDMA, UMTS, IP, GSM, LTE, WiMax, UMB, EV-DO, 802.11, BLUETOOTH, etc.

Processor 406 may be a processor dedicated to analyzing information received by receiver 402 and/or generating information for transmission by transmitter 420, a processor that controls one or more components of wireless communications device 400, and/or a processor that both analyzes information received by receiver 402, generates information for transmission by transmitter 420, and controls one or more components of wireless communications device 400. Further, signals may be prepared for transmission by transmitter 420 through modulator 418 which may modulate the signals processed by processor 406.

Processor 406 may be operable to provide means for receiving an interference indicator, and means for determining a service period end time from the interference indicator. Processor 406 may further include at least one processor enabled to perform one or more of the above described means.

Wireless communications device 400 may additionally include memory 408 that is operatively coupled to, and/or located in, processor 406 and that may store data to be transmitted, data that has been received, information related to available channels, data associated with an analyzed signal and/or interference strength, information related to an assigned channel, power, rate, or the like, and any other suitable information for estimating a channel and communicating via the channel. Memory 408 may additionally store instructions to implement protocols and/or algorithms associated with estimating and/or utilizing a channel (e.g., performance based, capacity based, etc.).

It will be appreciated that data store (e.g., memory 408) described herein may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. By way of illustration, and not limitation, nonvolatile memory may include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable PROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in many forms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). Memory 408 of the subject systems and methods may include, without being limited to, these and any other suitable types of memory.

Wireless communications device 400 may further include communication module 430 to assist in communications. In an aspect, communications module 430 may include interference signaling module 132, which performs the above-described interference signaling functionality. For example, interference signaling module 132 may perform the process 200. Interference signaling module 132 may be a separate component on wireless communication device 400, or a part of communications module 430, or a part of memory 408, or a part of processor 406, or any combination thereof.

Additionally, wireless communications device 400 may include user interface 440. User interface 440 may include input mechanisms 442 for generating inputs into communications device 400, and output mechanism 444 for generating information for consumption by the user of the communications device 400. For example, input mechanism 442 may include a mechanism such as a key or keyboard, a mouse, a touch-screen display, a microphone, etc. Further, for example, output mechanism 444 may include a display, an audio speaker, a haptic feedback mechanism, a Personal Area Network (PAN) transceiver etc. In the illustrated aspects, the output mechanism 444 may include a display operable to present media content that is in image or video format or an audio speaker to present media content that is in an audio format.

Referring to FIG. 5, an example architecture of one aspect of an access point 120 (FIG. 1) with interference avoidance functionality is illustrated. Access Point 500 may include at least one of any type of hardware, server, personal computer, mini computer, mainframe computer, or any computing device either special purpose or general computing device programmed to perform the functionality described herein. Further, the modules and applications described herein as being operated on or executed by access point 500 may be executed entirely on a single network device, or alternatively, in other aspects, separate servers, databases or computer devices may work in concert to provide data in usable formats to devices, and/or to provide a separate layer of control in the data flow between communications devices 110, 130 and the modules and applications executed by access point 500.

Access point 500 may include a computer platform 502 that may transmit and receive data across wired and wireless networks, and that may execute routines and applications. Computer platform 502 may include memory 504, which may include volatile and nonvolatile memory such as read-only and/or random-access memory (ROM and RAM), EPROM, EEPROM, flash cards, or any memory common to computer platforms. Further, memory 504 may include one or more flash memory cells, or may be any secondary or tertiary storage device, such as magnetic media, optical media, tape, or soft or hard disk. Further, computer platform 502 may also include processor 530, which may be an application-specific integrated circuit (“ASIC”), or other chipset, logic circuit, or other data processing device. Processor 530 may include various processing subsystems 532 embodied in hardware, firmware, software, and combinations thereof, that enable the functionality of access point 500 and the operability of the network device on a wired or wireless network.

Processor 530 may be operable to provide means for receiving an interference indicator, and means for determining a service period end time from the interference indicator. Processor 530 may further include at least one processor enabled to perform that above described means.

Computer platform 502 may further include communications module 550 embodied in hardware, firmware, software, and combinations thereof, that enables communications among the various components of access point 500, as well as between access point 500, and devices 110, 130. Communication module 550 may include the requisite hardware, firmware, software and/or combinations thereof for establishing a wireless communication connection.

Computer platform 502 may further include service period (SP) determination module 134 operable for assisting access point 500 in reducing or avoiding interference in communications with one or more STAs, such as STAs 110 and 130 in FIG. 1. In one aspect, SP determination module 134 may perform all or some portion off the functionality described herein to reduce or avoid interference in communications with a STA. For example, SP determination module 134 may perform all or some of the process 200.

With reference to FIG. 6, illustrated is a system 600 for reducing interference according to one aspect. For example, system 600 can reside at least partially within a WCD, UE, etc. According to another exemplary aspect, system 600 can reside at least partially within an access point. It is to be appreciated that system 600 is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware).

System 600 includes a logical grouping 602 of means that can act in conjunction. For instance, logical grouping 602 can include means for receiving an interference indicator from a STA 604. In one aspect, the system 600 may receive the interference indictor using an 802.11 v protocol. In one aspect, the interference indicator may include a time indication for the service period end time. In another aspect, the time indication may be determined by the STA at a time prior to or coinciding with interference at the STA. In another aspect, the time indication may include a time period relative to transmission of a triggering frame transmission. In another aspect, the triggering frame may be includes a U-APSD Coexistence frame. In still another aspect, the time indication may include a TSF. In another aspect, the interference indicator may include a schedule of one or more start times of interference at the STA. In one such aspect, the schedule may include an offset relative to a TSF, an interval between occurrences of the one or more start times of the interference, etc. Further, logical grouping 602 can include means for determining a service period end time from the interference indicator 606. In one aspect, the means for receiving and/or the means for determining may be performed by at least one of a second STA, an access point, etc.

Additionally, system 600 can include a memory 608 that retains instructions for executing functions associated with the means 604 and 606. While shown as being external to memory 608, it is to be understood that one or more of the means 604 and 606 can exist within memory 608.

Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

It is understood that any specific order or hierarchy of steps described in the context of a software module is being presented to provide an examples of a wireless node. Based upon design preferences, it is understood that the specific order or hierarchy of steps may be rearranged while remaining within the scope of the invention.

The previous description is provided to enable any person skilled in the art to fully understand the full scope of the disclosure. Modifications to the various configurations disclosed herein will be readily apparent to those skilled in the art. Thus, the claims are not intended to be limited to the various aspects of the disclosure described herein, but is to be accorded the full scope consistent with the language of claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A claim that recites at least one of a combination of elements (e.g., “at least one of A, B, or C”) refers to one or more of the recited elements (e.g., A, or B, or C, or any combination thereof). All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to carry or store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes, compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. 

What is claimed is:
 1. A method of wireless communication for reducing interference, comprising: receiving an interference indicator from a station (STA); and determining a service period end time from the interference indicator.
 2. The method of claim 1, further comprising terminating a service period at or before the service period end time.
 3. The method of claim 1, further comprising determining an end to a service period at the service period end time.
 4. The method of claim 1, wherein the interference indicator comprises a time indication for the service period end time.
 5. The method of claim 4, wherein the time indication is determined by the STA at a time prior to or coinciding with interference at the STA.
 6. The method of claim 4, wherein the time indication comprises a time period relative to transmission of a triggering frame.
 7. The method of claim 6, wherein the triggering frame includes a U-APSD Coexistence frame.
 8. The method of claim 4, wherein the time indication comprises a timing synchronization function (TSF).
 9. The method of claim 1, wherein the interference indicator comprises a schedule of one or more start times of interference at the STA.
 10. The method of claim 9, wherein the schedule includes at least one of: an offset relative to a timing synchronization function (TSF); or an interval between occurrences of the one or more start times of the interference.
 11. The method of claim 1, further comprising: receiving a triggering frame.
 12. The method of claim 1, wherein the STA the interference indicator is received from comprises an access point.
 13. A computer program product, comprising: a computer-readable medium comprising code executable to: receive an interference indicator from a STA; and determine a service period end time from the interference indicator.
 14. An apparatus for wireless communications, comprising: means for receiving an interference indicator from a STA; and means for determining a service period end time from the interference indicator.
 15. An apparatus for wireless communications, comprising: a processing system; and a receiver configured to: receive an interference indicator from a first STA; and a service period determination module coupled to the processing system and configured to: determine a service period end time from the interference indicator.
 16. The apparatus of claim 15, wherein the service period determination module is further configured to terminate a service period at or before the service period end time.
 17. The apparatus of claim 15, wherein the service period determination module is further configured to determine an end to a service period at the service period end time.
 18. The apparatus of claim 15, wherein the interference indicator comprises a time indication for the service period end time.
 19. The apparatus of claim 18, wherein the time indication is determined by the first STA at a time prior to or coinciding with interference at the first STA.
 20. The apparatus of claim 18, wherein the time indication comprises a time period relative to transmission of a triggering frame.
 21. The apparatus of claim 20, wherein the triggering frame includes a U-APSD Coexistence frame.
 22. The apparatus of claim 18, wherein the time indication comprises a timing synchronization function (TSF).
 23. The apparatus of claim 15, wherein the interference indicator comprises a schedule of one or more start times of interference at the first STA.
 24. The apparatus of claim 23, wherein the schedule includes at least one of: an offset relative to a timing synchronization function (TSF); or an interval between occurrences of the one or more start times of the interference.
 25. The apparatus of claim 15, wherein the service period determination module is further configured to receive a triggering frame.
 26. The apparatus of claim 15, wherein the apparatus comprises at least one of a second STA or an access point. 